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Discussion Starter · #1 ·
Are there any Air Conditioner Improvement Mods?

Just got my AC competely charged.
Works OK except in the Hot Sun.
Then takes a while to cool down.
and
Not very well at Idle.

My Dad's 94 Roadmaster seems to be cooler and quicker.

Was wondering if there were any tricks to improve AC performance?
 

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Not really sure any mods are required as much as just making sure it is working as well as possible. There isn't really much you can do to the fundamental design of the system (evaporator and condenser areas are fixed).

I just went through mine recently and it is working as well as I remember my brand new Impala SS systems working. Cleaned the orifice screen, wiped down all of the seals with new oil, added new oil to the system, baked the accumulator/drier in the oven at 175ºF for about 8 hours, quickly threw it on the car, pulled the system down to -30" for a few mins, threw a quick charge without running the system and pulled it down to -30" again then charged it back up until the pressures were correct...with both fans running. Ice cold at idle in the current south Florida heat and the evaporator drain looks like a freaking faucet cwm4

All I can offer is:
  • make sure both fans run when it is warmed up and the A/C is on
  • make sure the condenser is clean
  • make sure the orifice is clean
  • insulate the cold line since the orifice is way up at the battery and the cold refrigerant has to go all the way back to the firewall past the hot engine
  • check the low/high pressure relationship carefully since this is where cold comes from
It's a lot more work, but if you are still unimpressed after all that, you may want to check that all of the mixer flaps are working correctly and the evaporator is as clean as possible.

EDIT: one last thing I forgot to mention was the fan thing. It turns out that replacement fans (the heater fan inside the I/P) have smaller squirrel cages with fewer blades. If you have ever replaced it, you might want to see if you have the newer (not) improved design that is moving less air than the original. There are pictures comparing the two floating around somewhere.
 

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My Dad's 94 Roadmaster seems to be cooler and quicker.
That shows that the basic system is a good one. It is the same on both cars. Scott's tips are good ones.

Is your dad's car a lighter color? Does it have the Sungate windshield and yours does not?

I was suprised at how much better my system worked when I evacuated it and put in exactly how much refrigerant it called for. I had previously used the pressure chart from the FSM and it was ok, but it worked a lot better with EXACTLY the amount called for.

You may consider this;
http://www.aircondition.com/vov/

but you would be adding a moving part that could fail, vs the bulletproof orifice tube. I bought one, but never installed it. Lost it in the moves.
 

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Discussion Starter · #4 · (Edited)
That shows that the basic system is a good one. It is the same on both cars. Scott's tips are good ones.

Is your dad's car a lighter color? Does it have the Sungate windshield and yours does not?

I was suprised at how much better my system worked when I evacuated it and put in exactly how much refrigerant it called for. I had previously used the pressure chart from the FSM and it was ok, but it worked a lot better with EXACTLY the amount called for.

You may consider this;
http://www.aircondition.com/vov/

but you would be adding a moving part that could fail, vs the bulletproof orifice tube. I bought one, but never installed it. Lost it in the moves.

I went to my buddies gas station and used his AC machine to blead the system all the way down.
Put in new oil and freon.
Works well but in hot sunny weather think it should be colder quicker.

May replace the Fan Motor and Fan Blade. The Motor is buzzing at high speed.

But is there a intake screen on these cars?

D
 

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No intake screen.

The VOV was discussed in this thread.

Use one of those reflective foldable windshield covers - it helps bigtime.

Do you have a crank underdrive pulley on your car? Are the idle speeds different?
 

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Read the web site.
Has anyone used the VOV?
Nope, not necessary IMHO. I just got done with my A/C system service. I installed a new compressor, receiver/dryer, orifice tube, sealing washers & O-rings all around. I added a few ounces of PAG-150 oil to the compressor's suction side, as well as a few ounces in the receiver/dryer.

I flushed the condensor and lines with acetone & compressed air, and buttoned the system up. Then installed a vacuum pump and drew a vacuum of 30" for 2 hours. I then turned off the pump, and made sure the system held the vacuum for another hour.

Per the manual, I installed 1Lb 12 Oz of freon on the low side. The pressures when I finished up were ~36 & 275. (80' & 60% humidity the other day when I did this)

With the fan on high, the temperature coming out of the RH center vent went down to 50'. I then drove the car about 10 minutes, and the temperature went down to 32'.

I did the same thing to my black 9C1 when I lived in Austin, and had the same results in 105' heat.

I'd suggest checking the system with a set of gauges, and compare to the readings to what is listed in the service manual (1 of 2) for the MAX pressures (Below).

 
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Need about $100 worth of manifold gauges and a vacuum pump. Also it's really not legal to vent refrigerant into the atmosphere, so sometimes better to pay shop when your system has leaked all the way out.
 

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if your system is working fine the only mod i can think of would be a pcm tune to have the fans come on sooner to help cool down the condenser. don't know how beneficial it would be?
 

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You can get the manifold gauges and a vacuum pump for AC systems at Harbor freight for less than $80 out the door(maybe a little more if you have it shipped). I had a friend who bought their gauges and vacuum pump and used it successfully on his Ford F150 truck. Harbor Freight may be inexpensive but they do sell some good stuff. - Peter
 

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if your system is working fine the only mod i can think of would be a pcm tune to have the fans come on sooner to help cool down the condenser. don't know how beneficial it would be?
Primary fan always comes on when the compressor is running. Programming may be able to turn the secondary fan on a little sooner. That may help a little.
 

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How hard is it/what is tools required for evacuating the system? Or is it better to have a shop do it?
As others have mentioned, you need a set of gauges, and a vacuum pump.

Here's an image, link and pricing for the gauges from Harborfreight:


$49.99 http://www.harborfreight.com/catalogsearch/result/?category=&q=134+gauges

And also a vacuum pump. The first shown is a one that you use with an air line from your shop compressor, and the second is an electric.

$12.99, http://www.harborfreight.com/catalogsearch/result/?category=&q=vacuum+pump+134


$79.99, http://www.harborfreight.com/25-cfm-vacuum-pump-98076.html

I would suggest checking the orifice tube for debris. It's located in the lower tube of the condensor at the threaded line connections near the battery. This would clue you in to knowing if there is any debris in the system.



$1.27, http://www.ackits.com/merchant.mvc?...=31-50006&Category_Code=Chevrolet96caprice5-7

If this looks like it has any particles/debris on it, especially in the screen area, I'd suggest flushing the system (Condensor, evaporator core, and lines). This is the proper way to flush the heat exchangers:

The Evaporator's inlet is at the bottom and therefore only one flush in the back flush direction (top to bottom).

The condenser's inlet is at the top and as with all heat exchanger flushing, this must be back flushed first (bottom to top).

I used the cheap flush stuff available from Advanced, and although it worked, I was happier using a fluid gun and acetone. The stuff from Advanced didn't evaporate fast, much at all after I flushed with it, and used compressed air to follow it up. Acetone will flush the system of contaminents (and water!), and evaporate quickly.

The next thing to do is replace the O-rings and sealing washers @ the compressor. O-rings can be bought from Ackits.com as well, and here's an image, pricing, and a link:



$10.51, http://www.ackits.com/merchant.mvc?...de=CP3016&Category_Code=Chevrolet96caprice5-7

The last thing is the sealing washers at the back of the compressor. I believe you'll need a 17MM socket to get that flange nut off. These are ~$10 at the stealership




I like the typical electric operated vacuump pump, as opposed to the super cheapie myself. I like to draw a vacuum on the system for at least an hour. Using the gauges & pump you should be able to pull 30" of vacuum without a problem. Then, I pull the plug on the vacuum pump, and leave it connected for another hour to ensure the system is holding a vacuum.

Then charge the system thru the gauges (R-134 gets connected to the center {yellow} hose, and thru the low pressure (blue) hose.

The last thing I'd highly suggest on replacing would be the accumulator (receiver/dryer). They're cheap, and it'll ensure you don't have moisture in the system



$15.60, http://www.ackits.com/merchant.mvc?...=37-23289&Category_Code=Chevrolet96caprice5-7

Good luck.
 

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I have used the vacuum pump that runs off compressed air, for years, with good results. However, now that electric pumps can be had for $80, I prefer them. I don't like running my compressor, for 30-45 minutes, to evacuate an AC system.

I also have Am American made R12 manifold set, which, of course, is better than my HF R134 manifold set (both get the job done).

TIP..just before you introduce the refrigerant into the vehicle, "purge" the manifold hose of air, by slightly lostening the fitting, at the vehicles service ports, to let a little R12/R143 push the air out.

READ UNDERSTAND ALL SAFETY RULES RE REFRIGERANT IF IT HITS YOUR EYE IN LIQUID FORM, YOU CAN GO BLIND. Also, if it contacts glowing hot metal, it can turn into a toxic gas.

If in dought, pay a pro.
 

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Lots of good info in this thread.

I bought those HF gauges and they leaked every where. Tightened up all the fittings on the manifold block and still leaked every where.
So back they went.



Any one else think this thread is Sticky worthy?
 

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Lots of good info in this thread.

I bought those HF gauges and they leaked every where. Tightened up all the fittings on the manifold block and still leaked every where.
So back they went.



Any one else think this thread is Sticky worthy?

MY HF gauges work good. I've used them on 5-6 cars
 

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Well driving to work tonight my a/c took a crap. Glad this thread is herecwm1

edit: turned out to be low freon. added dye to find my leak

MY HF gauges work good. I've used them on 5-6 cars
Looks like I'll be giving those gauges a try again and one of their vac pumps. Hope I just had a bad set last time.

I did and asked about it already. Looks like it just got stuck :D
It needed to be. It answers a lot of common questions asked about a/c work.
 

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I wish there was a compressor upgrade or something.

Nothing sucks worst than sitting in traffic andlooking at people with their hair blowing in the wind like some damn Beyonce video while I'm still boiling in mines. :-(
 
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